Means for damping electromechanical vibrator reeds



Feb. 17, 1953 J. B. DALE 2,629,033

MEANS FOR DAMPING ELECTROMECHANICAL VIBRATOR REEDS Filed April 27, 1950 Q :NVENTOR 1. l) JOSEPH DALE. Ei" "1&2 B2i I? ATTN s Patented Feb. 17, 1953 MEANS FOR DAMPING ELECTRO- MECHANICAL VIBRATOR REEDS Joseph B. Dale, Rockville Centre, N. Y., assigner to Servomechanisms, Inc., Mineola, N. Y., a corporation of New York Application April 27, 1950, Serial No. 158,398

(Cl. Zilli-90) 2 Claims.

This invention relates t0 electromechanical choppers or vibrators for periodically making and breaking an electric circuit and more particularly concerns a method and apparatus for controlling the action oi' the vibrating reed to eliminate bouncing and chattering of the contacts and provide smooth, uniform vibratory motion of the 'reed to obtain a positive make and break action of the contacts and lengthen the life of the reed. The above and other objects of the invention will become more apparent from the following` description and accompanying drawings.

In the drawings, Fig. 1 is a greatly enlarged cross-sectional view of a vibrator in accordance with the invention; Fig. 2 is an end view of the vibrator shown in Fig. l taken in the direction of arrow 2;

ig. 3 is an end view of the vibrator shown in Means have been suggested for preventing or '1" damping undesirable reed vibrations which ernploy either an auxiliary reed or other similar member engaging the main reed, or a main reed of composite structure. These methods of darnpthe reed have not 'been found to be entirely satisfactory as they merely eliminate one or two of the spurious or unwanted secondary vibrations of the reed. Moreover, these methods do not provide a shock absorbing action to slow down the reed just prior to the making of the contacts that would prevent any tendency for the contacts to bounce upon impact.

In the present invention means are employed in connection with the reed to effect air damping or" the reed over substantially its entire length and which damping not only prevents the production of low amplitude secondary vibrations of the reed but also causes the reed to slow down at each end of its stroke so that substantially all bounce of the contacts due to the making action is eliminated.

Brieny this air damping may be eiected by placing a rigid member in close proximity to each side of the reed with such members extend- 2 ing over substantially the entire length thereof or 'by completely surrounding the reed by a tubular member. The spacing is preferably made as close as possible but in any event should not limit the normal motion of the reed nor touch the reed during its vibration. This simple and effective reed damping system has been found to eifectively reduce spurious reed vibrations and provide shock absorbing action which so successfully eliminates undesirable contact bounce.

The invention is illustrated in the drawings as applied to a vibrator having a permanent magnet in combination with an electromagnet for alternately supplementing and opposing the magnetic eld 0f the permanent magnet to produce vibration of a reed.

In the drawings l0 denotes the vibrator housing preferably made of a non-magnetic material such as brass, Phosphor bronze and the like which holds the vibrating element. This housing lil in normal operation is placed within a surrounding magnetic coil l2 supported on a suitable coil form le.

The housing I0 is preferably of rectangular shape with a central section of the side and top walls removed to expose the vibrating reed l5.

In the lefthand end `of the housing IE! as shown in Fig. l is an elongated permanent magnet I8 that is approximately half the length of the housing iii and lies flat against the bottom wall 20 thereof. A brass channel 22 is fitted over the magnet to enclose the top and sides thereof to prevent the vibrator I6 from directly contacting the magnet i3. Overlying the magnet within the lefthand end of the housing it is a contact carrying member 2st having a contact 25 mounted on the inner end thereof. The other end of this member 2li extends beyond the end of the housing is to form an electric terminal for connecting the vibrator in an electric circuit. On top of the member 24 is a relatively heavy member 39 having a set screw 32 threaded in the inner end thereof and adapted to bear against the upper side of the member 24 for the purpose of adjusting the physical relationship of the contact 26 with the reed carrying contact 34. The members 2d and 35i together with a metal spacer 2S underlying the member 24 are insulated from the housing lil by insulating material 36 completely encircling the members. The members te, 2li and the magnet I8 together with the nonmagnetic channel 22 are held firmly within the housing by a set screw 38 threaded in the top wall of the housing l0 and bearing against a metal plate #it overlying the insulation 3B. To

prevent the set screw from loosening up during the operation of the vibrator it is preferable to peen the set screw slightly to deform the edge.

In the other end of the housing I0 a metal block 42 is positioned on the base 29 and extends from the righthand end of the housing to a point in close proximity to the righthand end of the magnet lil. The height of the block is substantially equal to the combined height of the magnet I8 and the enclosing channel 22. On the top of the block 40 rests a metal plate 44 and a thin sheet of insulation 4S which are co-extensive but somewhat shorter than the length of the block 42. The plate 44 and insulation 45 govern the spacing between the reed i6 which overlies the insulation 46 and the top face 48 of the block 42 and the upper side of the channel 22. The spacing 50 between the adjoining ends of the block 42 and the magnet i8 is preferably made as small as possible and the block 42 is preferably formed of a L non-magnetic material so as not to interfere with the action of the magnet i8.

Overlying the reed LB is another layer of insulating material 52 and a metal plate 54 which are identical with the corresponding elements 44 and 49 previously described and which determine the spacing between the reed it and an overlying metal plate 53S which extends from the righthand edge of the housing` i@ to a point in close proximi ty to the righthand end of the nXed contact carrying member 24.

In actual practice it has been found that with a reed having a thickness of about .003 inch and a free vibrating length of approximately 11/@4c inch, the spacing of the xed metal members from the reed (42 and 55 of Fig. 1) should be approximately .004 inch.

Overlying the metal plate 5t is another relatively heavy plate 58 which cooperates with a pair of screws l threaded in the top wall 62 of the housing l for holding the reed 'and its associated elements firmly in position.

In the operation of the vibrator which may be designed for operation of frequencies as high as 490 cycles to 800 cycles and even higher, the coniinement of the air between the face 48 of the metal block 42 and the lower face 56' of the block 56 successfully dampens spurious vibrations of the reed by impeding the flow of air in and about the reed itself. This action is also accomplished in part by the upper face of the channel 22 and it is lor this reason that the air gap E@ should be made as small as possible. Similarly the gap S4 between the members E and 24 should also be maintained as small as possible to obtain maximum damping effect. Moreover with the use of air damping the dampingl eiect increases as the reed approaches one or the other of the damping surfaces, so that a shock absorbing action results and this action coupled with damping of the spurious Vibrations of the reed produces uniform and positive making and breaking the contacts 2% and 34 and also results in lengthening the life of the reed. Furthermore by the elimination of damping means which actually contacts the reed and the avoidance of a reed of composite structure a material reduction in the manufacturing cost of the vibrator results with attendant improved operating characteristics.

An 'ap-proximate full-sized view of a vibrator in accordance with this invention is shown in Fig. 4 of the drawings and like numerals have been used to designate similar elements in this and the other gures previously described.

I claim:

1. In an electromechanical chopper having a contact carrying reed, a fixed contact for cooperation with the reed contact and means includ a pair of interacting magnets for vibrating the reed, damping means for the reed comprising means substantially coextensive with the reed and positioned closely thereto but out of contact therewith to impede the movement of air between said means and the reed.

2. An electromechanical vibrator comprising an elongated hollow housing of non-magnetic material, a permanent magnet mounted in one end of the housing, a contact supporting member including a fixed contact mounted in said one end of the housing in spaced relation to and overlying the magnet, a reed including a contact on its free end mounted in the other end of the housing with the free end of the reed overlapping the magnet and its Contact in operative relationship with said iixed contact, and a pair of parallel members spaced equidistantly on each side of the reed to confine the air in and about the reed duringl the vibration thereof.

JOSEPH B. DALE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date` 1,273,188 Savage July 23, 1918 1,997,477 Warnke Apr. 9, 1935 2,029,266 Leece et al. Jan. 28, 1936 2,308,549 Shapiro Jan. 19, 1943 2,471,594 Weightman May 31, 1949 FOREIGN PATENTS Number Country Date 393,398 Great Britain June 3, 1933 

